21242034551 has 4 divisors (see below), whose sum is σ = 21927261504. Its totient is φ = 20556807600.

The previous prime is 21242034533. The next prime is 21242034577. The reversal of 21242034551 is 15543024212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21242034551 - 2¹⁸ = 21241772407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242034511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 342613430 + ... + 342613491.

It is an arithmetic number, because the mean of its divisors is an integer number (5481815376).

Almost surely, 2^21242034551 is an apocalyptic number.

21242034551 is a deficient number, since it is larger than the sum of its proper divisors (685226953).

21242034551 is an equidigital number, since it uses as much as digits as its factorization.

21242034551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685226952.

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 21242034551 its reverse (15543024212), we get a palindrome (36785058763).

The spelling of 21242034551 in words is "twenty-one billion, two hundred forty-two million, thirty-four thousand, five hundred fifty-one".